//#pragma once

void LU_decompose(double **a, double **L, double **U);  // 法2.2
void Gauss_solver(double **a, double *x, double *b, int n);// 法2.4
void print_data(double** phi, double** eta, double **xx, char* buf);
void print_data2(double **phi, double *x, char *buf);